The current expectation of global geothermal energy through the end of the decade is that annual capacity installations will bring the existing approximately 12.6 GW to nearly 21.5 GW, with smaller increases in 2016-2017 giving way to larger annual increases from 2018-2020, according to data presented in April by Ruggero Bertani, geothermal business development manager for Enel, during the 2015 World Geothermal Congress.